Every year, billions of kilowatt-hours of electricity are consumed throughout the world for lighting purposes. Unfortunately, not all of the energy contained in that electricity becomes light. In fact, much of the energy is wasted. For example, it is not uncommon for incandescent lighting to have a luminous efficiency in the 2-3% range. Of course, different lighting technologies can have different energy conversion efficiencies, and several lighting technologies improve upon basic incandescent lighting. For example, practical light-emitting diode (LED) based lighting can have luminous efficiencies over 20%. A high luminous efficiency provides a good base to work from, but there are other factors that influence the overall efficiency of practical LED-based lighting systems (“LED lighting systems”).
Electric power is supplied for use in many different forms. For example, a basic difference is between direct current (DC) and alternating current (AC). Light-emitting diodes are typically designed to be powered by direct current. However, electric power is commonly distributed as alternating current. Consequently, conversion between the two forms (i.e., rectification) is a common feature of LED lighting systems. Losses during rectification, and power management in general, can be significant. In the context of the scale of the application, even small improvements are sought after.
Further efficiencies are possible if a lighting system is dimmable. For example, a user of the lighting system may adjust the output, and therefore the power consumption, of the lighting system in response to changing needs and, in particular, may dim the output when peak output is unnecessary. The lighting system may even be configured to dim automatically in response to ambient light conditions, for example, as part of a daylight harvesting system. However, not all power conditioning equipment is compatible with dimming functionality and/or conventional dimming components such as TRIAC-based dimmers.
Conventional solutions to efficiently powering a dimmable LED-based lighting system have shortcomings beyond energy losses. Some conventional solutions generate relatively high levels of electro-magnetic interference (EMI) including radio frequency (RF) noise. Some conventional solutions are impractically expensive and/or economically uncompetitive. Some conventional solutions behave poorly in contexts where relatively small form factors are desirable. Some conventional solutions scale poorly to smaller form factors. Some conventional solutions have relatively short operational lifetimes and/or a relatively high chance of failure, for example, because they use a relatively high number of components and/or use relatively low quality components to remain economically competitive.